DHCP assigns the same address to multiple machines

RouterOS Beginner Basics
1

Hello. I’ve set up network and ROS offers the same address to 2 machines connected. Here’s debug log:

19:19:42 dhcp,debug,packet dhcp-net1 received discover with id 1914728561 from 0.0.0.0 
19:19:42 dhcp,debug,packet     secs = 1 
19:19:42 dhcp,debug,packet     ciaddr = 0.0.0.0 
19:19:42 dhcp,debug,packet     chaddr = 08:00:27:6B:2E:EA 
19:19:42 dhcp,debug,packet     Msg-Type = discover 
19:19:42 dhcp,debug,packet     Client-Id = FF-E2-34-3F-3E-00-02-00-00-AB-11-B7-EF-BF-BB-87-3D-F8-D4 
19:19:42 dhcp,debug,packet     Parameter-List = Subnet-Mask,Router,Host-Name,Domain-Name,Domain-Server,Static-Route,Classless-Route,NTP-Server,Unknown(101) 
19:19:42 dhcp,debug,packet     Max-DHCP-Message-Size = 576 
19:19:42 dhcp,debug,packet     Host-Name = "TINTicket" 
19:19:42 firewall,info n_n input: in:net1 out:(none), src-mac 08:00:27:6b:2e:ea, proto UDP, 0.0.0.0:68->255.255.255.255:67, len 319 
19:19:43 dhcp,debug,packet dhcp-net1 sending offer with id 1914728561 to 10.0.1.254 
19:19:43 dhcp,debug,packet     ciaddr = 0.0.0.0 
19:19:43 dhcp,debug,packet     yiaddr = 10.0.1.254 
19:19:43 dhcp,debug,packet     siaddr = 10.0.1.1 
19:19:43 dhcp,debug,packet     chaddr = 08:00:27:6B:2E:EA 
19:19:43 dhcp,debug,packet     Msg-Type = offer 
19:19:43 dhcp,debug,packet     Server-Id = 10.0.1.1 
19:19:43 dhcp,debug,packet     Address-Time = 600 
19:19:43 dhcp,debug,packet     Subnet-Mask = 255.255.255.0 
19:19:43 dhcp,debug,packet     Router = 10.0.1.1 
19:19:43 dhcp,debug,packet     Domain-Server = 10.0.1.1 
19:19:43 dhcp,debug,packet     NTP-Server = 213.135.59.38 
19:19:43 dhcp,debug,packet dhcp-net1 received request with id 1914728561 from 0.0.0.0 
19:19:43 dhcp,debug,packet     secs = 1 
19:19:43 dhcp,debug,packet     ciaddr = 0.0.0.0 
19:19:43 dhcp,debug,packet     chaddr = 08:00:27:6B:2E:EA 
19:19:43 dhcp,debug,packet     Msg-Type = request 
19:19:43 dhcp,debug,packet     Client-Id = FF-E2-34-3F-3E-00-02-00-00-AB-11-B7-EF-BF-BB-87-3D-F8-D4 
19:19:43 dhcp,debug,packet     Parameter-List = Subnet-Mask,Router,Host-Name,Domain-Name,Domain-Server,Static-Route,Classless-Route,NTP-Server,Unknown(101) 
19:19:43 dhcp,debug,packet     Max-DHCP-Message-Size = 576 
19:19:43 dhcp,debug,packet     Server-Id = 10.0.1.1 
19:19:43 dhcp,debug,packet     Address-Request = 10.0.1.254 
19:19:43 dhcp,debug,packet     Host-Name = "TINTicket" 
19:19:43 dhcp,info dhcp-net1 assigned 10.0.1.254 to 08:00:27:6B:2E:EA 
19:19:43 dhcp,debug,packet dhcp-net1 sending ack with id 1914728561 to 10.0.1.254 
19:19:43 dhcp,debug,packet     ciaddr = 0.0.0.0 
19:19:43 dhcp,debug,packet     yiaddr = 10.0.1.254 
19:19:43 dhcp,debug,packet     siaddr = 10.0.1.1 
19:19:43 dhcp,debug,packet     chaddr = 08:00:27:6B:2E:EA 
19:19:43 dhcp,debug,packet     Msg-Type = ack 
19:19:43 dhcp,debug,packet     Server-Id = 10.0.1.1 
19:19:43 dhcp,debug,packet     Address-Time = 600 
19:19:43 dhcp,debug,packet     Subnet-Mask = 255.255.255.0 
19:19:43 dhcp,debug,packet     Router = 10.0.1.1 
19:19:43 dhcp,debug,packet     Domain-Server = 10.0.1.1 
19:19:43 dhcp,debug,packet     NTP-Server = 213.135.59.38 
19:19:43 firewall,info n_n input: in:net1 out:(none), src-mac 08:00:27:6b:2e:ea, proto UDP, 0.0.0.0:68->255.255.255.255:67, len 331 
19:19:44 dhcp,debug,packet dhcp-net1 received discover with id 3796715364 from 0.0.0.0 
19:19:44 dhcp,debug,packet     secs = 1 
19:19:44 dhcp,debug,packet     ciaddr = 0.0.0.0 
19:19:44 dhcp,debug,packet     chaddr = 08:00:27:40:CC:57 
19:19:44 dhcp,debug,packet     Msg-Type = discover 
19:19:44 dhcp,debug,packet     Client-Id = FF-E2-34-3F-3E-00-02-00-00-AB-11-B7-EF-BF-BB-87-3D-F8-D4 
19:19:44 dhcp,debug,packet     Parameter-List = Subnet-Mask,Router,Host-Name,Domain-Name,Domain-Server,Static-Route,Classless-Route,NTP-Server,Unknown(101) 
19:19:44 dhcp,debug,packet     Max-DHCP-Message-Size = 576 
19:19:44 dhcp,debug,packet     Host-Name = "TINClient" 
19:19:44 dhcp,info dhcp-net1 deassigned 10.0.1.254 from 08:00:27:6B:2E:EA 
19:19:44 dhcp,debug,packet dhcp-net1 sending offer with id 3796715364 to 10.0.1.254 
19:19:44 dhcp,debug,packet     ciaddr = 0.0.0.0 
19:19:44 dhcp,debug,packet     yiaddr = 10.0.1.254 
19:19:44 dhcp,debug,packet     siaddr = 10.0.1.1 
19:19:44 dhcp,debug,packet     chaddr = 08:00:27:40:CC:57 
19:19:44 dhcp,debug,packet     Msg-Type = offer 
19:19:44 dhcp,debug,packet     Server-Id = 10.0.1.1 
19:19:44 dhcp,debug,packet     Address-Time = 600 
19:19:44 dhcp,debug,packet     Subnet-Mask = 255.255.255.0 
19:19:44 dhcp,debug,packet     Router = 10.0.1.1 
19:19:44 dhcp,debug,packet     Domain-Server = 10.0.1.1 
19:19:44 dhcp,debug,packet     NTP-Server = 213.135.59.38 
19:19:44 dhcp,debug,packet dhcp-net1 received request with id 3796715364 from 0.0.0.0 
19:19:44 dhcp,debug,packet     secs = 1 
19:19:44 dhcp,debug,packet     ciaddr = 0.0.0.0 
19:19:44 dhcp,debug,packet     chaddr = 08:00:27:40:CC:57 
19:19:44 dhcp,debug,packet     Msg-Type = request 
19:19:44 dhcp,debug,packet     Client-Id = FF-E2-34-3F-3E-00-02-00-00-AB-11-B7-EF-BF-BB-87-3D-F8-D4 
19:19:44 dhcp,debug,packet     Parameter-List = Subnet-Mask,Router,Host-Name,Domain-Name,Domain-Server,Static-Route,Classless-Route,NTP-Server,Unknown(101) 
19:19:44 dhcp,debug,packet     Max-DHCP-Message-Size = 576 
19:19:44 dhcp,debug,packet     Server-Id = 10.0.1.1 
19:19:44 dhcp,debug,packet     Address-Request = 10.0.1.254 
19:19:44 dhcp,debug,packet     Host-Name = "TINClient" 
19:19:44 dhcp,info dhcp-net1 assigned 10.0.1.254 to 08:00:27:6B:2E:EA 
19:19:44 dhcp,debug,packet dhcp-net1 sending ack with id 3796715364 to 10.0.1.254 
19:19:44 dhcp,debug,packet     ciaddr = 0.0.0.0 
19:19:44 dhcp,debug,packet     yiaddr = 10.0.1.254 
19:19:44 dhcp,debug,packet     siaddr = 10.0.1.1 
19:19:44 dhcp,debug,packet     chaddr = 08:00:27:40:CC:57 
19:19:44 dhcp,debug,packet     Msg-Type = ack 
19:19:44 dhcp,debug,packet     Server-Id = 10.0.1.1 
19:19:44 dhcp,debug,packet     Address-Time = 600 
19:19:44 dhcp,debug,packet     Subnet-Mask = 255.255.255.0 
19:19:44 dhcp,debug,packet     Router = 10.0.1.1 
19:19:44 dhcp,debug,packet     Domain-Server = 10.0.1.1 
19:19:44 dhcp,debug,packet     NTP-Server = 213.135.59.38 
19:19:44 firewall,info n_n input: in:net1 out:(none), src-mac 08:00:27:40:cc:57, proto UDP, 0.0.0.0:68->255.255.255.255:67, len 319 
19:19:44 firewall,info n_n input: in:net1 out:(none), src-mac 08:00:27:40:cc:57, proto UDP, 0.0.0.0:68->255.255.255.255:67, len 331 
19:20:24 system,info,account user tin logged in via local
2

Linux by default uses UUID as Client-ID for dhcp. Those were 2 cloned VMs with the same UUIDs. Changing Client-ID source to mac solved the issue.
Just in case anyone has similar issue - options are:

  • change UUID
  • set unique MAC and set Client-ID source to MAC ([DHCP] ClientIdentifier=mac with systemd)
  • manually override DUID (UUID used for Client-ID) (eg. [DHCP] DUIDType=vendor ; DUIDRawData=00:00:ab:11:f9:2a:c2:77:29:f9:5c:00)